Let-off motion



July 23, 1968 A. SCHIAPPA 3,393,708

LET 'OFF MOT ION Filed Sept. 29, 1966 INVENTOR. A? 4v ro/v/o Uh/MP! ATTORNEY Y -"*'3,393,708 f I LET-OFF MOTION" Antonio Schiappa, Pawtucket, R.I.=,' assignor to J ohnson=& Johnsomacorporation of'New-Jersey.- i g 7. Filed Sept. Z9,,19 6 6, el'. No. 582,809

. 4. Claims. (Cl..13 9 -1 00) ABSTRACT, OF. DISCLOSURE.

A let-off motion for a warp beam comprising parallel members spaced above' arid perpendicular to the'w'arp beam shaft" and' said memb'ers being connected"at their front andrear portions by barsparallel to the shaft. The shafthas abrak'e' drum on one end along witha-brake strap for controlling the warp beam rotation; The tension,

on yarns pulled from the warp beam about the front bar is controlled by weights placedon the rear bar.

This invention relates toalet-off motion for th ebeams off under extreme control in order to prevent the formation I of stripes in the fabric. If the warp yarns are not let off at a constant tension, they will be woven tightly for awhile while the tension is drawn taut, at which point the warp beam jerks and allows for a loose weave forming a stripe in the fabric. Standard let-off motions presently used, for the part, do not have sufficient control of the tension to completely eliminate the formation of stripes when weaving with elastic warp yarns.

The let-off motion of the present invention gives excellent control of the tension applied to elastic yarns and prevents the formation of stripes when weaving narrow elastic fabrics. The let-off motion of the present invention also gives suitable control over the warp yarn beam immaterial of the diameter of the beam, that is, it has the same type of control over the large diameter beam and maintains that control as the beam is used and becomes very small in diameter. The let-off motion of the present invention also allows for a much less run of the elastic yarn from the warp beam to the weaving operation which reduces the breakage of the yarns during the weaving operation. The let-01f motion of the present invention also has the advantage that when the warp beam is used up, my let-off motion stays in place and does not drop out of the way greatly simplifying the rethreading when changing warp beams. Furthermore, the let-01f motion of the present invention takes reduced space and is very suitable for weaving operations wherein a series of warp beams are required.

The let-off motion of the present invention comprises a pair of spaced apart side bars spaced above and perpendicular to the warp beam shaft. A brake is mounted at one end of the warp beam shaft directly beneath one of the side bars. The brake comprises a band or strap attached to approximately the center of the side bar. The strap passes about the perimeter of a pulley mounted in a stationary manner on the warmp beam shaft and the strap is attached back to the side bar at a point closer to the front end of the bar. Mounted between the front ends of the side bars and parallel to the warp beam shaft is a round bar. Warp yarns are guided from the Warp beam about this round bar to be fed to any standard 3,393,708 Patented July 23, 196 8 Flce weaving loom. Mounted between the back ends o'f'the side bars is aifiat bar for carrying the weights to control the exact tension to be placed on the warpyarns. J

In operation, if tension is placed 'on the warp yarns, they in turn pull the round bar' downwardly allowing for slackin thestrap of the brake and allowing the warp beam tolet off warp yarns; whereas ifthere is too muchslack in the warp yarns, the weights will cause the round bar to ris'eputting more pressureon the brake preventing any motion in thewarp beam. 4 v I The invention will be more fully described when taken in conjunction with the accompanying drawings wherein: FIGURE 1 is a fragmentary side view 'of the let-off motionof the present'invention, and I I V FIGURE 2 is a top view of said let-off motion.

Similar reference numerals refer to like parts in each view.

Referring to the drawings, there is shown the necessary framing 10 upon which warp beams 11 may be mounted for use in weaving operations. Journaled in bearings 12 mounted in the frame is a shaft 13 upon which the warp beam is stationarily mounted. Also mounted on this shaft in a stationary manner is a suitable brake drum 14. Pivotally mounted on the same frame but above the warp beam shaft is the let-off motion 15. The let-off motion comprises two spaced-apart side bars 16 and 17 mounted perpendicular to the shaft 13. The side bars are connected at'their front edge by a stationary round bar 18, at their rear edge by a flat bar 19 suitable'for carrying weights 20 and at their midpoints by a middle round bar 21. The round bar 21 may extend through the side bars and be pivotally mounted in the frame 10 as shown in FIGURE 2. However, the side bars 16 and 17 must be secured at their mid-points to the round bar 21 so that the entire let-off motion is pivotally mounted in the frame as mentioned above and there is no slippage between the round bar 21 and the side bars 16 and 17. One of the perpendicular side bars is positioned directly above the brake drum so that the brake strap or band may be connected directly to the middle bar 21. The band 22 is Wrapped about the brake drum and then hooked back into one of the three smaller holes 23 placed in the side bar closer to the front round bar. These holes allow variance in the gross tension placed by the strap on the brake drum and may be varied dependent upon the elasticity in the yarn to be fed by the let-off motion. The warp yarns 25 are taken from the beam and fed over the middle round bar and the front round bar to the weaving operation. In operation, as tension is placed on the warp yarn, the front round bar is urged downwardly raising the rear weights and releasing the tension placed by the strap on the brake drum allowing more warp yarn to be fed off. If the tension in the warp yarns is too little, the rear weights keep suflicient tension on the strap of the brake drum to prevent any let off of the warp yarn.

The counterbalancing of the rear Weights and the front round bar provide for excellent control of the tension applied to the warp yarns, and just slight changes in tension will allow the warp beam to let-off or stop letting off warp yarns. This counterbalancing action also prevents any jerking motion in the warp beam. When starting operation, the warp beam is fully wound providing for a large diameter let-off, and when the warp beam is almost used, this diameter is much smaller; however, the counterbalancing action of the let-off motion provides excellent control of the tension immaterial of the diameter of the warp beam.

As may be seen from the drawings, the warp yarns are fed directly from the front round bar to the weaving operation, and the distance between the front round bar and the warp beam is quite short. With this short run of warp yarns, there is much less chance of breakage of the yarns as contrasted to standard let-off motions Where yarn runs are quite extensive placing much greater stress on the warp yarns.

In the let-off motion of the present invention when the warp beam is used up and no further tension is placed on the front round bar, the let-off motion still remains in place as the rear weights place tension on the strap at the brake drum holding the let-off motion in its operating position for ready replacement of the warp beam.

The invention in its broader aspects is not limited to the specific mechanism shown and described, but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

What is claimed is:

1. A let-off motion for a warp beam comprising spaced parallel side members, spaced above and perpendicular to the shaft carrying said warp beam, said parallel side members being connected at their front portion by a first bar and at their rear portion by a second bar, said bars being parallel to the shaft carrying said warp beam, a brake drum on said shaft of said warp beam positioned directly below One of said parallel members and a brake strap passing about the periphery of said brake drum, a first end of said strap being connected to said parallel member directly above said brake drum and the second end of said strap also being connected to the same parallel member but spaced a slight distance from said first end whereby if warp yarns are pulled about said first bar to place tension thereon, said tension may be counter balanced by placing Weights on said second bar.

2. A let-off motion in accordance with claim 1 wherein said first bar is a stationary round bar and said second bar is a stationary fiat bar.

3. A let-off motion for a warp beam comprising spaced parallel side members, spaced above and perpendicular to the shaft carrying said warp beam, said parallel side members being connected at their front portion by a first bar, at their rear portion by a second bar and at their midpoint by a third bar, said bars being parallel to the shaft carrying said warp beam,'a brake drum on said shaft of said warp beam,positioned directly below'onexofsaid parallel side members and a brake strap passing about the periphery of said brake'drum, afirst endof said strap being connected to said third bar immediately adjacent said parallel side member and directly above said brake drum and the second end of said strap being connected to said parallel side member but spaced-"a"slight distance from said first end whereby if warp yarns are pu-lled'about said first bar to place tension thereon, saidtension may be counterbalanced by placing weights on said second bar.

4. A let off motion according toclaim 3 wherein said first and third bars are stationary round bars and said second bar is a stationary fiat bar,

References Cited UNITED STATES PATENTS MERVIN STEIN, Primary Examiner, J. KEE CHLAssistant Examiner. 

